1. Field of the Invention
The present invention generally relates to a pneumatic bearing arrangement and more specifically to a pneumatic bearing arrangement in which outer and inner conical elements are separated by a bearing space and a journal member of a shaft is rotatably and floatably supported within the space.
Generally, most shaft bearings for high speed rotational elements employ either a ball or roller bearing or a hydraulic bearing which is operable to hydraulically form high pressure forced oil films about the periphery of a journal section of a shaft in order to rotatably support the section in floating fashion. For even greater, extra-high speed rotational regions which must support a journal section, bearings utilizing repulsive magnetic forces and pneumatic bearings utilizing pneumatic forces, which both reduce frictional resistance of the bearings against shaft rotation to a minimum, are utilized.
The arrangement of the present invention involves a pneumatic bearing arrangement particularly useful for application in the extra-high speed rotational regions referred to hereinabove. As used throughout this specification, the phrase "pneumatic bearing arrangement" defines the combined structure of a pneumatic bearing and a journal section or member or other part of a shaft.
2. Description of Prior Art
Conventional pneumatic bearing arrangements exist in which compressed air is jetted into a very small gap between a cylindrical bearing member and a journal section or member of a solid shaft which is rotatably positioned within the bearing member in floating fashion by air films formed by the jetted, compressed air. These conventional arrangements are both theoretically and structurally analogous to the hydraulic bearings referred to hereinabove, the only difference being that compressed air is used in the conventional pneumatic arrangements whereas pressurized oil is utilized in the hydraulic bearings.
In order for conventional pneumatic bearing arrangements to satisfactorily function in extra-high speed rotational situations, however, these arrangements must operate so as to support a journal member or section in a contactless, floating condition which will exist even when both radial and thrust loads are applied to the journal section or member, i.e., the structure must be capable of bearing loads both in the radial and thrust directions and meet the apparently structurally contradictory requirements that the journal section or member have a reduced mass or weight and an increased total pressure receiving area, insofar as is possible.
Additionally, such pneumatic bearing arrangements must be provided with means for preventing axial removal of the shaft connected to the journal, the shaft conventionally comprised by a diametrically extending flange on the shaft and a thrust bearing which receives the flange in order to bear the thrust load applied to the shaft. Consequently, such bearing is enlarged and elongated and the mass or weight of the journal section is increased due to the presence of the flange; furthermore, air circuitry within the thrust bearing is complicated by the added parts.
Alternately, even if the journal section or member is provided with a deformation so as to have a substantially angular cross-section for enabling the section or member to bear both radial and thrust loads, the section or member is still formed as a solid shaft and has a relatively large mass or weight by itself. Additionally, if the diameter or length of the journal section or member is increased in order to desireably increase its total pressure receiving area, the mass of the section is also further increased, thereby failing to satisfy the hereinabove referred to desireable structural requirements; accordingly, the practical functions desired to be met by the arrangement cannot be satisfactorily achieved.
Accordingly, conventional pneumatic bearings may be adapted for use in raised speed situations within a speed range determined by the substitution of compressed air for the pressurized oil of hydraulic bearings; this arrangement, however, lacks the lubricating function/application achieved at extra-high speeds by hydraulic bearings.